Macro layout verification appartus

ABSTRACT

A macro layout verification apparatus for verifying a layout of a macro to be placed as a functional block on a semiconductor device. The apparatus includes: a unit, which assumes as a virtual wiring line, a wiring line that uses an unused intra-macro channel located adjacent to an intra-macro wiring line; a unit which calculates a parallel wiring length along which the virtual wiring line and the intra-macro wiring line run; and a unit which outputs information concerning the virtual wiring line when the parallel wiring length exceeds a reference value defined as a design rule.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.12/785,624, filed May 24, 2010, issued as U.S. Pat. No. 8,286,117, whichis a continuation of PCT/JP2007/075178, filed on Dec. 27, 2007, theentire contents of both applications are incorporated herein byreference.

FIELD

Embodiments discussed herein are related to an apparatus for verifyingthe layout of a macro designed as a functional block in the developmentprocess of a semiconductor device, such as an LSI.

BACKGROUND

As depicted in FIG. 1, when designing an LSI (Large Scale Integrated)circuit, first the layout of a macro itself as a functional block isdesigned in accordance with design rules (step 102). Next, the macro isplaced on the LSI and inter-macro wiring is made (step 104). Finally,the entire LSI and the layout of the macro on the LSI are verified (step106).

Since the layout within the macro is referred to when verifying the LSIlayout, the amount of data to be handled increases, resulting in anincrease in processing time. Further, macro terminals have to beconnected on the LSI in order to place the macro on the LSI and makeinter-macro wiring, but if there are not enough channels to connect theterminals, the macro cannot be placed and wired on the LSI.

Furthermore, even when the layout of the macro itself satisfies thedesign rules, there can occur cases where the relationship between theLSI wiring and the intra-macro wiring fails to satisfy the design ruleswhen the macro is placed and wired on the LSI. For example, a ruleviolation associated with the parallel wiring of the LSI wiring andintra-macro wiring may be detected. In this way, problems that can occurdue to interference between the layout within the macro and the LSIwiring when the macro is placed and wired on the LSI cannot be detectedunless the macro is actually placed and wired on the LSI.

In designing the layout of the LSI, if an error occurs in the layoutverification in relation to the intra-macro wiring, the intra-macrowiring cannot be modified without greatly affecting the design process.To address this, a method is employed that prohibits the use of wiringchannels located adjacent to the intra-macro wiring during the LSIwiring so that the macro can be placed and wired on the LSI withouthaving to be conscious of the layout within the macro. However, indesigning the layout of the LSI, if the use of wiring channels locatedadjacent to the intra-macro wiring is prohibited, a problem occurs inthat the number of channels available for use decreases, resulting in adegradation of wiring characteristics.

Patent document 1 cited below as a prior art document related to thepresent invention discloses an LSI design rule verification methodwherein the verification of design rules is made by considering thehierarchy used in automatic layout. On the other hand, patent document 2cited below discloses a functional macro design method that achievesconnectivity having a high degree of wiring freedom without violatingthe design rules when connecting with other cells.

Patent document 1: Japanese Unexamined Patent Publication No. H05-102307

Patent document 2: Japanese Unexamined Patent Publication No.2000-269341

SUMMARY

According to an aspect of the invention, a macro layout verificationapparatus for verifying a layout of a macro to be placed as a functionalblock on a semiconductor device includes: a unit configured to assume asa virtual wiring line a wiring line that uses an unused intra-macrochannel located adjacent to an intra-macro wiring line; a unitconfigured to calculate a parallel wiring length along which the virtualwiring line and the intra-macro wiring line run; and a unit configuredto output information concerning the virtual wiring line when theparallel wiring length exceeds a reference value defined as a designrule.

The object and advantages of the invention will be realized and attainedby means of the elements and combinations particularly pointed out inthe claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and arenot restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart depicting the sequence of prior art macro layoutverification;

FIG. 2 is a block diagram depicting the hardware configuration of amacro layout verification apparatus according to one embodiment;

FIG. 3 is a schematic flow diagram of macro layout verificationaccording to one embodiment;

FIG. 4 is a flowchart illustrating a procedure for verifying parallelwiring length;

FIG. 5 is a diagram depicting an example of how the parallel wiringlength is verified;

FIG. 6 is a flowchart illustrating a procedure for verifying connectionsof a macro terminal to via contacts;

FIG. 7 is a diagram depicting an example of how the connections of themacro terminal to via contacts are verified;

FIG. 8 is a flowchart illustrating a procedure for verifying feedchannels of the macro terminal;

FIGS. 9A, 9B, and 9C are diagrams depicting an example of how the feedchannels of the macro terminal are verified; and

FIGS. 10A, 10B, and 100 are diagrams for explaining how the feedchannels of the macro terminal are checked.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention will be explained with reference tothe accompanying drawings.

FIG. 2 is a block diagram depicting the hardware configuration of amacro layout verification apparatus according to one embodiment. Asillustrated, the macro layout verification apparatus according to thepresent embodiment is implemented by running a macro layout verificationprogram on a conventional workstation (WS) which comprises a computermain unit 210 having a central processing unit (CPU) 212 and a mainstorage (MS) 214, a display 220 as an output device, a keyboard 222 asan input device, a mouse 224 as an input device, and a hard disk device230 as an auxiliary (external) storage device.

FIG. 3 is a schematic flow diagram of macro layout verificationaccording to one embodiment. As depicted in the diagram, first thelayout of a macro as a functional block is designed (step 302). Next,the macro layout verification according to the present embodiment isperformed (step 304). Then, the macro is placed on the LSI andinter-macro wiring is made (step 306).

As depicted in FIG. 3, in the macro layout verification (step 304),macro layout information 310, information 312 defining LSI wiringlayers, wiring line widths, via contact geometry, etc., and design rules314 are taken as inputs, and a verification result 320 on the macroitself and information 322, such as information concerning wiring linesthat can cause an error in the LSI design layout, are output. Theverification result 320 on the macro itself is fed back to the design ofthe macro. On the other hand, the information 322, such as theinformation concerning wiring lines that can cause an error in the LSIdesign layout, is used when placing and wiring the macro on the LSI.This serves to avoid an error that can occur after the placement andwiring, achieving a reduction in the number of layout steps.Furthermore, the wiring characteristics can be enhanced by makingeffective use of the wiring channels within the macro.

In the present embodiment, the first item of the macro layoutverification concerns verifying the parallel wiring length at the timeof LSI circuit wiring. When two wiring lines run in parallel in closeproximity to each other, crosstalk noise can occur; therefore, in thelayout rules, the maximum allowable length (parallel wiring length)along which two wiring lines run is defined according to the wiring linewidth, the spacing between the two wiring lines, etc. In the presentembodiment, the verification of the parallel wiring length is performedto verify whether or not the layout within the macro satisfies the LSIlayout rules when unused channels within the macro are used for thewiring of the LSI circuit. FIG. 4 is a flowchart illustrating aprocedure for verifying the parallel wiring length, and FIG. 5 is adiagram depicting an example of how the parallel wiring length isverified.

First, information defining the wiring layers of the LSI circuit and thewiring line width used in each wiring layer is acquired from the layoutconditions of the LSI circuit (step 402). When a plurality of wiringlayers are defined for the LSI circuit, information defining theplurality of wiring layers is acquired in advance. Further, when aplurality of wiring line widths are defined for the respective wiringlayers, information defining the plurality of wiring line widths isacquired in advance.

Next, for each intra-macro wiring line, unused wiring channels in theLSI circuit that are located adjacent to that intra-macro wiring lineare detected as virtual wiring channels, and a virtual wiring centerline is set that interconnects the detected virtual wiring channels(step 404). The unused wiring channels to be detected here are thosethat are formed in the same wiring layer as the wiring layer containingthe intra-macro wiring line, that satisfy the spacing requirements ofthe intra-macro wiring, and that are closest to the intra-macro wiringline. For LSI fabrication reasons, a prescribed spacing must be providedbetween a metal forming a given intra-macro wiring line and a metalforming another intra-macro wiring line; therefore, spacing rules aredefined that prohibit the use of channels located within the prescribedspacing distance from the boundary of the intra-macro wiring line, thespacing distance being determined according to the wiring line width.

In the example of FIG. 5, virtual wiring center lines 511, 513, and 515are set for the intra-macro wiring line 500. Since channel 520 violatesthe spacing rules, no virtual wiring center line is set between thechannels 520 and 522. In step 404, all the virtual wiring center lines(each defined by the wiring layer and the channels) that can be set foreach intra-macro wiring line are acquired.

Next, from among the thus set virtual wiring center lines, one virtualwiring center line for assuming the virtual wiring line to be verifiedis extracted (step 406). Then, the wiring line width information isretrieved that is used for the wiring layer in which the extractedvirtual wiring center line is placed (step 408). If there is a pluralityof such wiring line width information, a given one of the plurality ofpieces of wiring line width information is retrieved. Next, the wiringline width retrieved in step 408 is applied to the virtual wiring centerline extracted in step 406, and the resulting wiring line is assumed asthe virtual wiring line to be verified (step 410).

In the example of FIG. 5, for the virtual wiring center lines 511, 513,and 515, the wiring lines 512, 514, and 516, each provided with aphysical wiring line width, are assumed as the virtual wiring lines tobe verified.

Next, the parallel wiring length is calculated that represents thelength along which each virtual wiring line assumed in step 410 as thevirtual wiring line to be verified runs in parallel with the intra-macrowiring line (step 412). Then, it is determined whether or not thecalculated parallel wiring length exceeds a specified value (referencevalue) defined in the design rules (step 414).

If the calculated parallel wiring length exceeds the specified value, areport indicating the possibility of an error is output, and at the sametime, the wiring layer, wiring line width, and channel informationassociated with that virtual wiring line is output as the informationconcerning the wiring line that can cause an error in the LSI circuitdesign layout, and the information is stored on the hard disk device 230(FIG. 2) (step 416).

Further, if the parallel wiring length exceeds the specified value, itis determined whether there is a channel one step farther away from theintra-macro wiring line than the channel in which the virtual wiringline has been assumed (step 418); if there is such a channel, a virtualwiring line is set for that channel, and the process returns to step412.

In the example of FIG. 5, if the virtual wiring line 516, for example,is found to cause an error, it is determined whether there is a channelone step farther away from the intra-macro wiring line than the channelswhere the virtual wiring line 516 is placed. Since there are channelsone step farther away, a virtual wiring line 518 interconnecting suchchannels is assumed, and it is verified whether or not the virtualwiring line 518 causes an error. If the virtual wiring line 518 causesan error, it is determined whether there is a channel located stillfarther away, and the process for verifying the virtual wiring lineinterconnecting such channels is repeated. Then, the conditions underwhich the virtual wiring line causes an error are stored. The virtualwiring line verification is repeated until there is no longer any error.

When the verification is completed for a given wiring line width, it isdetermined whether the verification is completed for all the wiring linewidths (step 422); if there is any wiring line width yet to be verified,the process returns to step 408 to retrieve the wiring line widthinformation. Then, the virtual wiring line verification is performedbased on the retrieved wiring line width.

When the verification is completed for all the wiring line widths for agiven virtual wiring center line, it is determined whether theverification is completed for all the virtual wiring center lines (step424). If there is any virtual wiring center line yet to be verified, theprocess returns to step 406 to extract the virtual wiring center lineinformation. Then, the virtual wiring line verification is performed forthe extracted virtual wiring line. When the verification is completedfor all the virtual wiring center lines, the routine is terminated.

In the present embodiment, the second item of the macro layoutverification concerns verifying the connections of a macro terminal tovia contacts. This verification is performed to verify whether or notthe relationship between each via contact and the layout within themacro satisfies the layout rules when the via contact is placed on themacro terminal for the inter-macro wiring on the LSI circuit. FIG. 6 isa flowchart illustrating a procedure for verifying the connections of amacro terminal to via contacts, and FIG. 7 is a diagram depicting anexample of how the connections of the macro terminal to via contacts areverified.

First, unused channels on the macro terminal are detected as feedchannels (step 602). In the example of FIG. 7, it is assumed that feedchannels 702-1, 702-2, and 702-3, for example, are detected on the macroterminal 700.

Next, assuming that via contacts are placed on all the feed channels, itis checked to see whether or not the spacing between each via contactand the intra-macro wiring line adjacent to it satisfies the designrules (step 604). In the example of FIG. 7, via contacts 704-1, 704-2,and 704-3 are assumed. Then, for each assumed via contact 704, thespacing D from the intra-macro wiring line 706 adjacent to it ischecked.

Next, the result of the check in step 604 is evaluated (step 606). If itis determined that, for all of the assumed via contacts, the spacing Dfrom the adjacent intra-macro wiring line is smaller than a referencevalue and thus violates the design rules, an error message to thateffect is output and the information is stored on the hard disk device230 (FIG. 2) (step 608).

On the other hand, if it is determined that, for some of the assumed viacontacts, the spacing from the adjacent intra-macro wiring line violatesthe rules, in other words, there are feed channels that do not cause anerror, a warning message is output to the effect that an error can occurin the LSI circuit design layout, and the information is stored on thehard disk device 230 (step 610).

If, for all of the assumed via contacts, the spacing from the adjacentintra-macro wiring line satisfies the design rules, i.e., if there is noerror, the process is terminated without issuing any message.

In the present embodiment, the third item of the macro layoutverification concerns verifying the feed channels of the macro terminal.This verification is performed to verify whether or not the macrocontains an unused channel that can be brought out in a continuousfashion from the macro terminal to a designated wiring layer for theinter-macro wiring on the LSI circuit. The designated wiring layer hererefers to the wiring layer where the destination macro terminal, towhich signals from the macro terminal under verification are to be fed,is placed.

FIG. 8 is a flowchart illustrating a procedure for verifying the feedchannels of the macro terminal, and FIGS. 9A, 9B, and 9C are diagramsdepicting an example of how the feed channels of the macro terminal areverified. Specifically, the example of FIG. 9 depicts the case where thedesignated wiring layer is located one layer above the wiring layer inwhich the macro terminal under verification is placed. For convenience,the wiring layer in which the macro terminal is placed is referred to asthe lower layer, and the designated wiring layer as the upper layer;then, FIG. 9A is a diagram depicting the wiring on the upper layer in asuperimposed fashion on the wiring on the lower layer, FIG. 9B is adiagram depicting the wiring on the lower layer, and FIG. 9C is adiagram depicting the wiring on the upper layer.

First, the wiring layer containing the macro terminal is set as thetarget wiring layer, and channels covered by the macro terminal aredetected (step 802). Next, unused channels located in the vicinity ofthe detected channels are detected (step 804).

In the example of FIG. 9, the virtual wiring line 902 functions as themacro terminal. In FIG. 9A, a dashed line 904 and other dashed linesindicate the spacing provided around the wiring line. By carrying outthe steps 802 and 804, a total of 29 channels indicted by black dots inFIG. 10A are detected for the macro terminal 902 depicted in FIG. 9.

Next, those channels that are located in the spacing belonging to othermetal wiring lines are removed from the detected channels (step 806).

In the example of FIG. 9, six channels 1006 depicted in FIG. 10B areremoved as they are located in the spacing belonging to the metal wiringline 906, and two channels 1008 depicted in FIG. 10B are removed as theyare located in the spacing belonging to the metal wiring line 908. As aresult, the number of detected channels is given as 29−6−2=21.

Next, those channels that cannot be brought out to the adjacent wiringlayer on the designated wiring layer side are removed from the detectedchannels (step 808). The channels that cannot be brought out to theadjacent wiring layer each refer to a channel that becomes connected toa metal wiring line on the adjacent wiring layer or runs into thespacing belonging to it when a connection is made from that channel tothe adjacent wiring layer through a via contact.

In the example of FIG. 9, four channels 1020 depicted in FIG. 100 areremoved as they become connected to the metal wiring line 920 on theupper layer, and six channels 1022 depicted in FIG. 100 are removed asthey become connected to the metal wiring line 922 on the upper layer orrun into the spacing belonging to it. As a result, the number ofdetected channels is given as 21−4−6=11.

Next, it is determined whether the adjacent wiring layer is thedesignated wiring layer itself (step 810). If it is not, the targetwiring layer is shifted to the adjacent wiring layer (step 812), and theprocess returns to step 804, to repeat the above process based on thenumber of currently detected channels. On the other hand, if it is thedesignated wiring layer, the process proceeds to step 814.

In the example of FIG. 9, since the adjacent wiring layer is thedesignated wiring layer itself, the process proceeds to step 814.

In step 814, the number of currently detected channels is taken torepresent the number N of channels that can be brought out to thedesignated wiring layer in a continuous fashion, and the value of N isevaluated. If the value of N is “0”, since signals cannot be fed fromthe macro terminal to the designated wiring layer within the macro, anerror message to that effect is output and the information is stored onthe hard disk device 230 (step 816). If the value of N is not “0” but issmaller than a reference value R (for example, “10”), it is determinedthat signals may not be able to be fed to the designated wiring layer,so that an error message to that effect is output and the information isstored on the hard disk device 230 (step 818). If the value of N is notsmaller than the reference value R, the process is terminated withoutissuing any message.

In the example of FIG. 9, since the value of N is “11”, and thereference value R is set to “10”, the process is terminated withoutissuing any message. Finally, in the example of FIG. 9, it is determinedfor the macro terminal 902 that the channels indicated by x are thechannels that cannot be brought out and that the channels indicated by ◯(11 channels) are the channels that can be brought out.

According to the macro layout verification apparatus disclosed herein,since parallel wiring errors that can occur due to interference betweenthe intra-macro wiring and the wiring (inter-macro wiring) to be made atthe time of LSI layout design are detected in advance at the time of themacro layout verification, any error to be output at the time of the LSIlayout verification can be predicted and avoided in advance, whichserves to reduce the number of process steps required for the LSI layoutdesign.

Furthermore, according to the macro layout verification apparatusdisclosed herein, an error that can occur when connecting the macroterminal in the LSI design layout or the possibility of the occurrenceof such an error can be detected in advance when designing the macrolayout.

All examples and conditional language recited herein are intended forpedagogical purposes to aid the reader in understanding the inventionand the concepts contributed by the inventor to furthering the art, andare to be construed as being without limitation to such specificallyrecited examples and conditions, nor does the organization of suchexamples in the specification relate to a showing of superiority andinferiority of the invention. Although the embodiments of the presentinvention have been described in detail, it should be understood thatthe various changes, substitutions, and alterations could be made heretowithout departing from the spirit and scope of the invention.

What is claimed is:
 1. A macro layout verification apparatus,comprising: a unit configured to assume that a plurality of via contactsare respectively placed at different places on a terminal of a macrothat is a functional block of circuits on a semiconductor device; a unitconfigured to determine whether or not the relationship between each ofthe via contacts and a wiring line within the macro satisfies a designrule; and a unit configured to store a warning message when one of thevia contacts satisfies the design rule and another one of the viacontact does not satisfy the design rule.
 2. The macro layoutverification apparatus according to claim 1, wherein the differentplaces on the terminal are all unused channels.